I was pretty well set on going with the HTC One X (new EVO on Sprint), but the lack of an expansion slot and non-removable battery give me pause. On the other hand, the new Samsung has an expansion slot, a removable battery and a very slightly larger screen. Knowing that I'm just going to root it, I have to say initial blush tells me I should go with the Sammy.

I think for people that are going too flash their phone, the newest Galaxy is probably the best bet. I don't know much about CDMA phones, but you have to remember that this isn't the phone that Sprint will get. They'll get a branded, modified phone changed to support that network and whatever changes Sprint and Samsung want. This is the international GSM version - it'll never reach the US. We'll see different processors, different modems, etc. The original Galaxy S showed up on Sprint with a QWERTY keyboard...

Samsung seems to be doing better in supporting independent developers. The problem with flashing ROMs is that a lot of them don't do much. Generally, they take Cyanogen code and modify it, or simply port from a similar device (in this case, it'd be the international S III). While the code is open source, a lot of the hardware and drivers aren't. And that's when a lot of the performance issues come in when you flash ROMs. That's the difference between a Nexus phone and just flashing the latest ICS ROM that shows up. That's why I trash a lot of the Android "coding" community - but some of the them do decent stuff. They're just limited in what they can do.